| 1 | GU | AVIATECA, S.A. | ICAO: GUG, IATA Prefix: 240, Subsidiary of Grupo TACA. Name changed to Avianca Guatemala | GCA | AVCODES |
| 2 | GU | Empresa Guatemalteca de Aviacion (AVIATECA) | ICAO: GUG, IATA Prefix: 240, | GCA | AVCODES |
| 3 | GU | (G&U) Grafton & Upton R.R. Co. | 4/1970-7/2000; eliminated 1/2003; 7/2005 | | NAKINA |
| 4 | GU | (G&U) Grafton & Upton R.R. Co. | 4/70-7/2000 | | NRHS |
| 5 | GU | GRAFTON & UPTON RAILROAD COMPANY | | | PWRC |
| 6 | GU | Grafton and Upton Railroad | | | RSRV |
| 7 | GU | GRAFTON AND UPTON RAILROAD COMPANY | | | SCAC4 |
| 8 | GU | Grafton and Upton Railroad | | USA | TRAFFIC |
| 9 | GUA | Aerotaxis de Aguascalientes, S.A. de C.V. | Callsign: Aguascalientes, | MEX | AVCODES |
| 10 | GUA | Aerotaxis de Aguascalientes | | | ICAO1 |
| 11 | GUA | | City: Guadalajara | MEX | TRAFFIC |
| 12 | GUAD | GUARDIAN MOVING AND STORAGE | | | SCAC4 |
| 13 | GUAF | GUARANTEED AIR FREIGHT FORWARDING, INC | | | SCAC1 |
| 14 | GUAN | GUANGDONG ETERNAL WAY INTL FREIGHT | | | SCAC4 |
| 15 | GUANG | Guangzhou Metro | | PRC | TRAFFIC |
| 16 | GUAQ | GUARRIELLO TRUCKING LLC | | | SCAC4 |
| 17 | GUAV | GUAVA EXPRESS INC | | | SCAC4 |
| 18 | GUAX | Georgia Power Co. | added 10/1982; 1/1994; eliminated 10/1999; 7/2000 (not listed); added 10/2000; 7/2005 | | NAKINA |
| 19 | GUAX | Georgia Power Co. | added 10/82; 1/94; eliminated 10/99; 7/2000; added 10/2000 | | NRHS |
| 20 | GUAX | GEORGIA POWER COMPANY | | | PWRC |
| 21 | GUAX | Georgia Power | | | RSRV |
| 22 | GUAX | GEORGIA POWER COMPANY | | | SCAC4 |
| 23 | GUAY | GUAY, L P (1987) INC | | | SCAC4 |
| 24 | GUB | Gamla Uppsala Buss AB | City: Uppsala | S | TRAFFIC |
| 25 | GUBA | GARZA, UBALDO | | | SCAC4 |
| 26 | GUBE | GRUBE, BOB | | | SCAC4 |
| 27 | GUC | Puer General Aviation Co., Ltd. | IATA: R8, Callsign: Leaf Air, Designator R8 recalled by IATA | PRC | AVCODES |
| 28 | GUC | Puer General Aviation Co., Ltd. | Callsign: Leaf Air, Designator R8 recalled by IATA | PRC | AVCODES |
| 29 | GUCC | GULF ENERGY MARITIME (GEM) PJSC | | | SCAC4 |
| 30 | GUCG | GUNTHERS LOGISTICS LLC | | | SCAC4 |
| 31 | GUCI | GULF COAST INTERMODAL INC | | | SCAC4 |
| 32 | GUCK | GULICK TRUCKING INC | | | SCAC4 |
| 33 | GUDC | GREMIO UNIDO DE CHOFERES Y TRABAJAD | | | SCAC4 |
| 34 | GUDC | Gelligaer Urban District Council | | GB | TRAFFIC |
| 35 | GUDG | GUADALUPE DE GUAYMAS SPR DE RL | | | SCAC4 |
| 36 | GUDN | GUARIDIAN TRANSPORT LLC | | | SCAC4 |
| 37 | GUDQ | GUARANTEE DELIVERY SERVICE | | | SCAC4 |
| 38 | GUDR | GUILD OF AUTOMOTIVE RESTORERS, THE | | | SCAC4 |
| 39 | GUDU | GUD GESELLSCHAFT FUR UMWELDIENSTE M | | | SCAC4 |
| 40 | GUE | Aero Servicio Guerrero, S.A. de C.V. | Callsign: Aero Guerrero, | MEX | AVCODES |
| 41 | GUED | GUERRA CARDENAS, ARTURO | | | SCAC4 |
| 42 | GUEE | GULF EUROPE EXPRESS | | | PWRC |
| 43 | GUEI | GUERRA RODRIGUEZ, PABLO | | | SCAC4 |
| 44 | GUEQ | GTA-US EXPRESS INC | | | SCAC4 |
| 45 | GUEX | General American Marks Co. | added 1/1998; 7/2000-7/2005 | | NAKINA |
| 46 | GUEX | General American Transportation Corp. | added 4/1971; 1/1975-1/1994; eliminated 1/1998 | | NAKINA |
| 47 | GUEX | General American Transportation Corp. | added 4/71; 1/75-1/94; eliminated 1/98 | | NRHS |
| 48 | GUEX | General American Marks Co. | added 1/98; 7/2000 | | NRHS |
| 49 | GUEX | GENERAL AMERICAN MARKS CO. [GENERAL AMERICAN TRANSPORTATION CORP.] | | | PWRC |
| 50 | GUEX | General American Marks (GATX Corporation) | | | RSRV |
| 51 | GUF | Gulf African Airlines Limited | Callsign: Gulf African, | WAG | AVCODES |
| 52 | GUF | Gulf African Airlines - Gambia | | | ICAO1 |
| 53 | GUFM | GULF FLEET MANAGEMENT LLC | | | SCAC4 |
| 54 | GUG | AVIATECA, S.A. | IATA: GU, IATA Prefix: 240, Subsidiary of Grupo TACA. Name changed to Avianca Guatemala | GCA | AVCODES |
| 55 | GUG | Empresa Guatemalteca de Aviacion (AVIATECA) | IATA: GU, IATA Prefix: 240, | GCA | AVCODES |
| 56 | GUG | Aviateca | | | ICAO1 |
| 57 | GUGN | GLORY UNIVERSAL GROUP INC | | | SCAC4 |
| 58 | GUGT | GUGLIELMETTI TRUCKING LLC | | | SCAC4 |
| 59 | GUHB | GUTHRIE-HUBNER INCORPORATED | | | SCAC4 |
| 60 | GUIC | GUILES, CRAIG | | | SCAC4 |
| 61 | GUIE | GREENCORE USA INC | | | SCAC4 |
| 62 | GUIL | GUILFORD TRANSPORTATION INDUSTRIES, INC | | | PWRC |
| 63 | GUIN | GUINEY DELIVERY SERVICE INC | | | SCAC4 |
| 64 | GUIN | Guinness Tramway | | IRL | TRAFFIC |
| 65 | GUIR | GUIRO TRUCKING | | | SCAC4 |
| 66 | GUIS | GRACE UNIVERSAL INC | | | SCAC4 |
| 67 | GUIZ | GUNDERSON INDUSTRIES | | | PWRC |
| 68 | GUJ | Gujarat Airways Limited | IATA: G8, Callsign: Gujartair, IATA designator changed from G8* | IND | AVCODES |
| 69 | GUJ | Gujarat Airways Limited | IATA: G8, Callsign: Gujartair, IATA designator changed to G8 | IND | AVCODES |
| 70 | GUJ | Gujarat Airways | IATA: G8 | | ICAO1 |
| 71 | GUKI | GURU TRUCKING INC | | | SCAC4 |
| 72 | GUL | Gull Air | Callsign: Gull-Air, | USA | AVCODES |
| 73 | GUL | Gull Air | | | ICAO1 |
| 74 | GULA | GULF COAST ENERGY | | | SCAC4 |
| 75 | GULC | GUILDCREST TRANSPORTATION INC | | | SCAC4 |
| 76 | GULF | GUIGNARD FREIGHT LINES INC | | | PWRC |
| 77 | GULH | GAULT, L H & SON INC | | | SCAC4 |
| 78 | GULI | GULLY TRANSPORTATION, INC | | | SCAC1 |
| 79 | GULK | GULICK, KEVIN | | | SCAC4 |
| 80 | GULL | GULF TRANSPORT LLC | | | SCAC4 |
| 81 | GULT | GULFSIDE TRANSPORTATION INC | | | SCAC4 |
| 82 | GULV | GULF MOVING SYSTEMS | | | SCAC4 |
| 83 | GUM | Gum Air N.V. | Callsign: Gum Air, | SME | AVCODES |
| 84 | GUM | Gum Air | | | ICAO1 |
| 85 | GUMA | GULICK TRUCKING INC | | | SCAC4 |
| 86 | GUMM | GUINDON MOVING & STORAGE | | | SCAC4 |
| 87 | GUMO | GUINDON MOVING AND STORAGE | | | SCAC4 |
| 88 | GUMT | GUME TRANSPORT & STORAGE INC | | | SCAC4 |
| 89 | GUMV | GUM, V G & SON TRUCKING INC | | | SCAC4 |
| 90 | GUN | Grant Aviation, Inc. | IATA: GV, Designator GS* reinstated/changed by IATA | USA | AVCODES |
| 91 | GUN | Grant Aviation | IATA: GS | | ICAO1 |
| 92 | GUNB | GUNDLACH & SONS LEASING COMPANY INC | | | SCAC4 |
| 93 | GUND | GUNN, CLAUDE R | | | SCAC4 |
| 94 | GUNE | GUNTREN EXPRESS INC | | | SCAC4 |
| 95 | GUNG | GUNGEN DENIZCILIK VE TICARET A S | | | SCAC4 |
| 96 | GUNH | GUNTHERS TRANSPORT | | | SCAC4 |
| 97 | GUNI | GUNDI INC | | | SCAC4 |
| 98 | GUNN | GUNSON, R TRUCKING | | | SCAC4 |
| 99 | GUNS | GUNSON TRANSPORT | | | SCAC4 |
| 100 | GUPL | GROUPE LAJPAL | | | SCAC4 |
